Method and system for controlling an emergency device

Abstract

The invention relates to a method for controlling an emergency device of a helicopter, said helicopter comprising a rotor suitable for being rotated, said emergency device being suitable for supplying additional emergency propulsion power to the helicopter, in said method comprising a step ( 10 ) of measuring the rotation speed of the helicopter rotor, a step ( 12 ) of calculating the drift of the measured rotation speed, a step ( 20 ) of continuously verifying conditions such that the speed of rotation of the rotor is higher than a predetermined value, referred to as arming speed, and the drift of the rotation speed is lower than a predetermined value, referred to as arming drift, and a step ( 22 ) of activating the emergency device if the verified conditions are validated.

The invention claimed is: 
     
       1. A control method for an emergency device of a helicopter, said helicopter comprising a rotor adapted to be rotated, said emergency device being adapted to supply additional emergency propulsive power to the helicopter,
 said method comprising the following steps: 
 a step of measuring the rotation speed of the helicopter rotor, 
 a step of calculating the derivative of the measured rotation speed, 
 a step of detecting a drop in the rotation speed of the rotor at an instant t0 below the nominal rotation speed V NRnom  of the helicopter rotor, 
 a step of activating a timer to measure the duration Δt from the instant t0, the timer being activated as long as the rotation speed of the rotor is dropping, 
 a step of measuring at an instant t0+Δt the rotation speed of the rotor V NR , 
 a step of continuously verifying the following conditions: 
 the rotation speed of the rotor is greater than a predetermined value, called arming speed, 
 the derivative of the rotation speed is greater than a predetermined value, called arming derivative, 
 the derivative of the rotation speed at instant t0+Δt is lower than or equal to: 
 
       
         
           
             
               
                 
                   V 
                   DEC 
                 
                 - 
                 
                   V 
                   NR 
                 
               
               
                 Δ 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 t 
               
             
           
         
         the derivative of the rotation speed at instant t0+Δt is greater than or equal to: 
       
       
         
           
             
               
                 
                   V 
                   DEC 
                 
                 - 
                 
                   V 
                   NRnom 
                 
               
               
                 Δ 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 t 
               
             
           
         
         with V DEC  being the stall speed of the helicopter rotor, below which the helicopter is in stall due to the loss of lift of the helicopter, 
         an activation step of the emergency device if the verified conditions are validated. 
       
     
     
       2. The control method according to  claim 1 , wherein the verification step verifies the following additional condition:
 the derivative of the rotation speed is greater than a predetermined value, called disarming derivative. 
 
     
     
       3. A control system for an emergency device of a helicopter, said helicopter comprising a rotor adapted to be rotated, said emergency device being adapted to supply additional emergency propulsive power to the helicopter, said control system comprising:
 an input adapted to receive a measurement of the rotation speed of the helicopter rotor, 
 calculation means adapted to carry out the control method according to  claim 1 , 
 an ignition output configured to transmit an activation order to the control device if the verified conditions are validated by said control process. 
 
     
     
       4. The control system according to  claim 3 , further comprising a supply input adapted to transmit electrical energy which allows the calculation means to operate and to transmit the activation order to the control device. 
     
     
       5. The control system according to  claim 3 , further comprising a status output, adapted to transmit information relative to the operating status of the control system. 
     
     
       6. The control system according to  claim 3 , further comprising a plurality of inputs adapted to receive information from the helicopter sensors and/or information from the emergency device sensors. 
     
     
       7. A helicopter comprising said emergency device according to  claim 3 . 
     
     
       8. A control method for an emergency device of a helicopter, said helicopter comprising a rotor adapted to be rotated, said emergency device being adapted to supply additional emergency propulsive power to the helicopter,
 said method comprising the following steps: 
 a step of measuring the rotation speed of the helicopter rotor, 
 a step of calculating the derivative of the measured rotation speed, 
 a step of detecting a drop in the rotation speed of the rotor at an instant t0 below the nominal rotation speed VNRnom of the helicopter rotor, 
 a step of activating a timer to measure the duration Δt from the instant t0, the timer being activated as long as the rotation speed of the rotor is dropping, a step of measuring at an instant t0+Δt the rotation speed of the rotor VNR, a step of continuously verifying the following conditions: 
 the rotation speed of the rotor is greater than a predetermined value, called arming speed, 
 the derivative of the rotation speed is greater than a predetermined value, called arming derivative, 
 the derivative of the rotation speed at instant t0+Δt is lower than or equal to: 
 
       
         
           
             
               
                 
                   V 
                   DEC 
                 
                 - 
                 
                   V 
                   NR 
                 
               
               dt 
             
           
         
         the derivative of the rotation speed at instant t0+Δt is greater than or equal to: 
       
       
         
           
             
               
                 
                   V 
                   DEC 
                 
                 - 
                 
                   V 
                   NRnom 
                 
               
               
                 Δ 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 t 
               
             
           
         
         with VDEC being the stall speed of the helicopter rotor, below which the helicopter is in stall due to the loss of lift of the helicopter, 
       
       an activation step of the emergency device if all the verified conditions are validated.